Flight History
On 20 November 1998, the pilot of a Cessna 182Q (registration HB-CJK) intended to fly from Speck-Fehraltorf airfield to Altenrhein. After arriving, he removed the cover, cleaned the aircraft of a light snow layer, stowed parachute equipment, and obtained a favorable weather report for the destination. He then started the engine and performed a 15-minute warm-up on the ground due to cold temperatures. Subsequently, he taxied to the fuel pump, checked the drain at three points, and refueled with 95 liters. After filing a flight notification, he restarted the engine, conducted a checklist, and taxied to the holding point for runway 12 without applying carburetor heat.
The takeoff on runway 12 toward Lake Pfäffikon was normal. The aircraft gained usual altitude with no irregularities. Over the lake at about 200 m above ground, a sudden power loss occurred; engine RPM dropped from 2400 to 2000 or below. The pilot applied full carburetor heat, which temporarily improved the situation, raising RPM to about 2300. He considered returning to the departure airfield. However, at the eastern end of the lake, power dropped again, and he saw no possibility to maintain altitude. The pilot selected a field on the left side that appeared to be a meadow, aligned with the wind. With the engine still running but insufficient power, he attempted a landing. The aircraft touched down in a nose-high attitude on the main wheels. When the nose wheel contacted the ground, it immediately sank into the only superficially frozen terrain, causing the aircraft to overturn at approximately 1410 local time, about three minutes after takeoff.
The pilot remained uninjured. The aircraft sustained substantial damage; minor third-party property damage occurred.
Investigation Findings
The pilot held a valid license and had sufficient recent training, though not extensive total experience. No evidence of medical impairment was found. The aircraft was properly maintained and approved for VFR day operations. The last 100-hour inspection was on 27 August 1998 at 224.07 hours; at the accident, total airframe time was 257.03 hours. Weight and balance were within limits.
Visual inspection of the recovered aircraft revealed no pre-existing technical defects. Ice accumulation on the airframe at the accident site did not affect control surface movement or aerodynamic properties. Examination of the carburetor (type Precision MA-4-5) showed no malfunctions: jets were clean and correct, the accelerator pump functioned properly, and the float chamber level was slightly below normal.
The selected landing area (marshland adjacent to Lake Pfäffikon) was suitable for a forced landing. Due to several days of low temperatures, the ground was only superficially frozen and insufficiently load-bearing for landing.
Meteorological Conditions
Switzerland was on the southwestern flank of a high-pressure system over Denmark, with a strong bise wind and moderate turbulence. Moist air was being fed into lower layers, causing local light snow showers. According to the Swiss Meteorological Institute, cloud cover in the accident area was 1-2/8 with a base at 3500-4000 ft. Temperature/dew point were –2°C/–7°C. Wind was 5-6 kt, gusting to 10-15 kt. Local observations showed dew point rising to –5°C during snowfall, then dropping back to –6°C to –8°C, while air temperature remained between –2.1°C and –2.5°C. The conditions indicated potential for light icing, with a tendency toward serious icing during snow showers.
A test run conducted on 2 December 1998 under similar temperature and humidity conditions showed normal engine start, warm-up, and a three-minute run at takeoff power with no anomalies or carburetor icing signs; carburetor temperature measured –9°C.
Carburetor Icing Assessment
Carburetor icing was considered very likely the cause of the power loss. In engines with constant-speed propellers, the onset of ice may first be indicated by changes in manifold pressure rather than RPM. The atmospheric conditions at the time were conducive to carburetor icing. The initial power loss and subsequent partial recovery after applying carburetor heat are consistent with this phenomenon. The failure to regain full power may have resulted from incomplete ice removal, possibly from ice formed earlier during ground operation or flight.
Probable Cause
The accident was a forced landing with overturn following a power loss, the cause of which was probably carburetor icing.